Detergent



Patented Oct. 9, i934 BE'EEEGENT Harry K. Mg and Arthur S. Butterwortb, Columbus, Ohio No Drawing. Applicahon Uctober 29, 1932, Serial No. teaser t perms This invention relates to solid detergent compositions, particularly for household use.

Various materials have been added to water to obtain detergent efiects, among which are borax, i tri-sodium phosphate, the common washing alkalies, e. g. sal soda, and others. Sodium metasilicate has been shown to have outstanding properties in this regard, and in fact it is reputed to be the best solid detergent. Generally the water m used in various household cleaning operations,-

such as in laundering, dish washing, etc., is advantageously treated with such agents. However, for household use it has been diflicult to use these solid detergents properly, because they have 31$ been available only in loose powdered, or crystalline,.form which is not conducive to convenient regulation of the proper quantities by the average home user. As a result too little of the detergent material may be used, which is inefiicient and not productive of the desired softening. More usually, however, in order surely to cause softening the average household'worker adds an excessive amount. This results in excessive alkalinity of the water, wastage of the material, and with $5 some of these detergentsit results in the formotion of an excessive amount of an undesirable It is among the objects of this invention to provide solid detergents in the form of shaped masses which permit convenient and proper dosing of water by household workers, are readily soluble in water, suflicient mechanical strength to permit merchandising and handling, may be made easily and cheaply, and in whose formation non-detergent (inert) materials are unnecessary. The invention is predicated on our discovery that tri-sodium phosphate exerts a plasticizing action on sodium metasilicate, and that by virtue of this shaped masses of coherent nature may be made readily. Water alone does not plasticize sodium metasilicate, i. e. mixtures thereof with water cannot be molded satisfactorily, because the molded articles swell, do not dry quickly, and are mechanically weak. Other means commonly M used for such purposes, such as water glass, are wholly. unsuited also. In accordance with our very, however, tri-sodium phosphate in the presence of water not only plasticizes sodium metaailicate so as to permit its ready molding, but

- also confers other substantial advantages. For instance, plastic mixes of these two solids with water set very rapidly, and the products are suitably strong. This makes it possible to mold pellots, tablets, or the like shaped masses containing uniform amounts of detergent material, for accurate dosing of water by unskilled users.

The shaped masses thus made from sodium metasilicate and tri-sodium phosphate in ac cordance with this invention possess suflicient Bi) mechanical strength to permit the handling necessary to marketing and use, but they dissolve readily in water, and they are completely detergent, i. e. they are free from non-detergent binders and other inert materials. Moreover, and of particular advantage, they are effective to produce appropriate softening action, since it is necessary only to add one or more pellets to obtain a predetermined effect, depending on the size of the pellets and the volume of water in use.

Our tests have shown that other detergent ma.- terials do not possess this ability to plasticize sodium metasilicate or other alkaline washing compounds. The reason why sodium phosphate exerts this action is not known to us, but apparently there is some reaction between the two compounds when water is added. Both sodium metasilicate and tri-sodium phosphate possess endothermic heats of solution. On the other hand, we have discovered that when intimate mixtures of .00 these two solids are treated with sufllcient water to form a plastic mix there is a large evolution of heat, 1. e. the mass becomes quite hot. The exothermic character of this reaction increases with increasing percentages of the silicate in the mixture, at least up to about 75 percent of the silicate. Presumably there is some reaction between the silicate and phosphate, but its exact nature is obscure, as will appear from a consideration of the compounds and their properties, so and it is not referred to in treatises on chemistry. Whatever be the nature of the action by which the tri-sodium phosphate plasticizes sodium metasilicate, the fact is that plastic mixtures of these two agents with water evolve a substantial amount of heat, they may be molded readily, the mixtures set hard within a very few minutes, and the formed masses are hard enough to permit their handling without danger of breakage.

In the practice of the invention mixtures of 1oo crystalline sodium metasilicate (NaaSiOa.5H:O) and tri-sodium phosphate (NasPO4.12H2O) in practically all proportions can be formed into plastic masses with water. For most purposes, however, it is preferred to make the shaped masses from mixtures composed of about 75 percent of the silicate, and 25 percent of the phosphate. In any case just enough water is added so that when kneaded the mixture is plastic. For

example, an intimate m xture of 3 pounds of the 0 'a desired softening action. That is, by making the tablets of uniform weight they exert a deflnite softening action when added to a given volume of water, and guess work on the part of the user is eliminated, so that it thus becomes possible for the user to obtain an optimum softening effect. Thus, the pellets may be made of such weight that the addition of one of them to a dish pan of water produces the proper softening action. This avoids waste and the production of excess alkalinity, it insures proper softening, and it makes it possible always to obtain the same softening effect. Thus all of the disadvantages of the loose, or bulk, detergent materials heretofore used are overcome. A further advantage is that the shaped masses are free from inert binders; they are composed wholly of materials active in softening. The ease of preparation makes it possible also to manufacture them cheaply, as no complicated apparatus is necessary, and drying or hardening operations are unnecessary.

The tablets can be made into any shape desired.

Preferably theirsurface is increased in order to accelerate solution, although they dissolve rapidly without this. For example, they may be perforated, or the surfaces may be provided with proiections of various shapes.

This plasticizing action of tri-sodium phosphate may be applied also as an aid to the molding of the other common solid washing alkalies, although the setting action is not quite so rapid as in the case of sodium metasilicate, and usually there is no such evolution of heat as occurs with the metasilicate. Other detergent materials apparently do not possess this plasticizing action. Sodium metasilicate when bonded by means of water glass, for example, gives very sticky masses {which do not dry hard. Moreover, tri-sodium phosphate alone when mixed with water alone {requires many hours for setting. This also hi dicates that the rapidity with which, setting occurs in mixtures of the phosphate and sodium metasilicate involves some reaction.

According to the provisions of the patent statutes, we have explained the principle of 'our invention and have described what we now consider to be its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

We claim:

1. As a new article of manufacture, molded detergent pellets formed from a mixture of a major proportion of crystallized sodium metasilicate, a minor proportion of crystallized tri-sodium phosphate, and sufficient water to render the mixture plastic, the pellets containing a predetermined quantity of the composition, and being coherent, easily soluble in water, and eflfective to produce uniform detergent action.

2. As a new article of manufacture, molded detergent pellets formed from a mixture of about percent of crystallized sodium metasllicate, and about 25 percent of crystallized tri-sodium phosphate, and sufflcient water to render the mixture plastic, the pellets containing a substantially uniform quantity of the composition, and being coherent,-easily soluble in water, and effective to produce uniform detergent action.

3. A method of bonding sodium metasilicate into coherent, easily solublemasses comprising forming a uniform mixture of a major proportion of said silicate with a minor proportion of tri-sodium phosphate said phosphate acting as a plasticizer for said silicate, adding suflicient water to render the mixture plastic, and molding the mixture to form shaped masses of uniform content of said mixture.

4. A method of bonding sodium metasilicate agents into coherent, easily soluble masses, comprising forming a uniform mixture of about 75 percent of said silicate with about 25 percent of tri-sodium phosphate said phosphate acting as a plasticizer for said silicate, adding sufficient water 'to render the mixture plastic, and molding the mixture to form shaped masses of uniform content of said mixture.

HARRY K. IHRIG.

ARTHUR S. BUI'I'ERWORTH. 

